Tungsten: The Perfect Metal For Bullets And Missiles

magine a lump of iron the size of a tennis ball. Weigh it in your hand. Now let it drop on to your foot. How does that feel? Now imagine an identical object three times as dense. How would that feel if you dropped it? Would you ever walk again?

That metal is tungsten.

As well as being incredibly dense it is also incredibly hard and has the highest melting point of all the elements at 3,422C.

A century or so ago the world had no use for it - it was almost impossible to shape or work the stuff. Yet now we use tungsten to write with, to traverse glaciers, to emit X-rays and to destroy buildings without the use of explosives.

To understand how this happened, we need to understand the competitive forces that have shaped everything in our world, and where better to start than a mystery at the heart of the evolution of life?

For the first four billion years, life didn't actually do much evolving. Organisms were small, simple and fairly rare. Then around 500 million years ago something extraordinary happened - the fossil records show there was an incredible explosion of life.